Loud-speaking receiver



Feb. 7, 1928. 1,658,349 I c. R. MOORE LOUD SPEAKING RECEIVER Filed March26. 1926 'IIIIIIIIIIIIIII Patented Feb. 7, 1928.

UNITED STATES PATENT OFFICE.

CHARLES R. MOORE, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y. A CORPORATION OF NEW YORK.

LOUD-SPEAKIN G RECEIVER.

Application filed March 26, 1926. Serial No. 97,640.

This invention relates to vibratory systems and more especially to suchsystems in which there is an intervening member between the vibratingpart and the element causing the vibration.

In systems of the above nature it is at times necessary to compensatefor the expansion and'contraction of the various parts. In the case ofmetallic elements such changes are due primarily to changes intemperature, while in non-metallic parts, such changes may be due tovariations in the amount of moisture, in the atmosphere, more commonlyknown as humidity, as well as changes in temperature. 7

An object of this invention is to compensate for the dimensional changesof a vibratory system so as to maintain the overall efficiency of thesystem substantially constant.

In certain vibratory systems manual means has been provided toaccomplish the above object. However, it has been found that frequentlmore trouble than benefit results when a justment is made by persons notsufficiently versed in the accomplishment of this purpose. The meansprovided by this invention eliminates any manual changes, thedimensional changes of the parts being taken care of automatically.

The above object is attained through the use of a. flexible, orsemi-flexible, member which connects the drivin element to the .driverlelement, this mem er being main- 3 tained taut by a weight, or similardevice, The inertia of the weight members is such that they are notaffected b the vibrations set up by the driving mem er, such vibrationsbeing transmitted directly and with only slightly diminished intensityto the driven member.

The invention will be more thoroughly understood from the followingdescription, in connection with the attached drawings giving specificembodiments thereof and in which:

Fig. 1 represents a hornless or cone type loud speaker element, which isquite common in radio work, to which the flexible member and weight havebeen applied, Fig. 2 represents, somewhat more in detail, the connectionof the flexible member through the armature ol. the driving element,Fig. 3 shows the invention as. applied to the mechanical type ofamplifier, Fig. 4 represents a means for compensating for variations inthe strength or flexibility of the intermediate member, and Figs. 5 and6 re resent alterna tive means which maybe use in place of the weightalone.

Referring more particularly to Fig. l the driving member or motorelement 10 is supported by frame 11 of the cone, substantially as shown.A string or other flexible member 13 is permanentlyfixed to the apex ofthe cone 12 and passes through a small hole or eyelet in the lower partof the armature 14 of the motor element. Suspended on this string, afterit has passed through the eyelet, is a weight 15 which is attached tothe frame by means of a spring 16.

The armature 14 of the motor element is moved between the pole. piecesof a magnet in accordance with electric vibrations impressed on thewindings of the motor element. The weight 15 is so chosen and thetension in the spring 16 is such that the natural period of thecombination is far removed from the periods of vibration of thearmature. For the small amplitudes and at the frequencies with which thearmature will be vibrated, that portion of the string extending from thearmature to the fixed point on the frame, and which includes the inertiamembers, acts substantially as a rigid lever pivoted at the fixed point.As used herein the term inertia members includes'weight 15 and spring16. \Vith this arrangement the energy of the armature is transmittedthrough'the string to the cone surface with only a very small loss tothe inertia members. It will be readily seen that. since the apex of theconc is not fixed to a rigid member and since the inertia members willrespond to slow movements, any dimensional changes in the cone surfacedue to atmospheric changes will be edmpensated for and the strinmaintained under tension. There will then ie no buckling or warping ofthe surface and the position of the armature relative to the polesof-the magnet will remain unchanged. Changes in the frame members,armature, etc, will also be taken care of in the same way.

In Fig. 3 the invention is shown as ap plied to a mechanical amplifier.This amplifier is well known in the art and consists of a drum 1? aroundwhich string 13 passes.

The drum is rotated at high speed from any suitable source by means of abelt 18 or similar arrangement. Any dimensional changes will betransmitted through string 13 to the inertia members with the drum l'i"acting as a slidingsurface or as a pulley.

In Fig. 4 an additional spring 19 is shown which compensates for anychange in flexibility of the string 13.

Fig. 5 shows a substitute for the weight 15 and spring 16 and consistsof a cyiin er 20 containing a semi-fluid substance 21, such as heavyoil, wax, etc. A piston 22 is immersed in the semi-fluid substance andstring 13 is attached to this piston either directly or through anintermediate still red. It will be readily seen that any rapid motion ofpiston 22 will be opposed by the material in the cylinder but that anygradual movement thereof, which may be occasioned by the change indimensions of the cone surface, will be permitted.

Another-method which may be substituted for the weight and spring isshown in Fig. (i and consists of the ordinary dash pot'arrangement. Themain piston 23 is hollow and encloses a number of sheets ot-paper,

metal foil, etc., on either side of piston 22 which provides bookdamping for the piston, which is well known in the'ar't. The result hereis the same asfor the piston in the sen'ii-fiuid of Fig. 5. Slow changesare permitted but to rapidibrations the dash pot arrangement acts asajfixed member.

W'hat is claimed is:

1. In avibratory system, an electromag netic element having a movablearmature, a

sound radiatorj to be vibrated,- a non-rigid member fr'ic tionallyconnected to said movable armature, one end of whlch 1s attached to saidsound radiator, and a. 'tensionmg means applied to the other end of saidnonrigid member. i

2. In combination, an electromagnetic responsive means, a soundradiator, a. nonrigid member connected at one end to said sound*adiator' and bearing frictionally against and electromagneticresponsive to said sound radiator, and a member, not

responsive to hi h frequency vibrations, attached to said d exiblemember to maintain the same under tension.

4. In a vibratory system, an electromagnetic element having a movablearmature, a sound radiator to be vibrated, and a flexiblememberconnected at. one end to said diaphragm and atthe otherend to atensioning means, said armature frictionally supporting said flexiblemember between its ends.

5. In a vibratory system, an electromag netic ele-menthaving a movablearmature and a sound radiator, and means for coinpensating for changesother than those due to vibrations from said armature in-the-po sitionof said radiator relative to said armature, saidmeans comprising aflexible element bearing against said armature and connected at one endto said diaphragm and at the other end to a tensioning means.

In witness whereof, I hereunto subscribe my name this 22 day of March A.D., 1926.

- CHARLES R. MOORE.

